1. Field of the Invention
The present invention relates to a composition for backing carpets in which an inorganic filler is blended in high concentrations. More particularly, the present invention relates to a carpet-backing composition having improved processability during heat blending, a high degree of flexibility, and, a particularly good performance at low temperatures, said composition being prepared by adding a synthetic oil having a particular structure when the inorganic filler is blended in high concentrations with an olefin-polar monomer copolymer.
The present invention further relates to a carpet for an automobile and to so-called carpet tiles in which said composition is backed onto a carpet in a molten form.
Carpets for automobiles are interior materials to be used for internal trim or decoration, and for providing effective heat insulation, soundproofing against engine noise or the like, and internal sound absorption. Backing materials for automobile carpets are required to perform the basic functions of reinforcing the carpet, imparting shape retaining properties thereto, preventing pile shedding, preventing shrinkage, and so on. A demand for improvement in comfort inside the car by reducing external noise such as engine noise has also been made. In order to meet this demand, backing materials having good soundproofing performance are required. Soundproofing performance is proportional to the mass per unit area of the backing material, so that the backing material is required to have a high density and some degree of thickness. Accordingly, it is desirable that a backing material having soundproofing properties in addition to performing other carpet functions is produced from low cost materials.
Carpet tiles are pieces of carpet in the shape of a square, rectangle, rhombus or the like or of a more complex shape, having an area of, for example, 0.05 to 2 m.sup.2. The carpet tiles can be fitted next to each other to closely cover the floor. Carpet tiles have an advantage over ordinary carpets in that laying is easily performed merely by placing the carpet tiles side by side and fixing them. Carpet tiles also have the merit that they can provide a variety of visual impressions by using different combinations of shape and color, and the repair thereof is easy. In instances where the carpet tiles are laid on the floor, it is required that they adhere sufficiently to the floor so that no portion thereof is disturbed during use. Methods of adhering the carpet tiles to the floor include those in which an adhesive or a self-adhesive is employed or in which each tile is fastened with nails or rivets; however, these methods have the drawbacks that both laying and relaying are laborious and time-consuming. As a means of avoiding such labor-intensive laying, carpet tiles are known which may be fixed by their own weight, such carpet tiles being designed to have a sufficient weight for self-fixing by comprising a relatively thick backing material.
Backing materials for carpet tiles are also required to provide fiber-shedding prevention, dimensional stability, elasticity and various other properties to the carpet tiles. Backing materials for carpet tiles should, as a matter of course, provide those properties required of backing materials for general carpets together with further fixability to such a degree that the carpet tiles may be fixed merely by being laid on the floor. Further, this fixability should be provided without using expensive raw materials.
2. Description of the Prior Art
Backing materials for carpets are known of the rubber latex type, the elastomer type, the synthetic resin type and the asphalt type. They are disclosed in, for example, Japanese Patent Publication Nos. 3,839/1971, 20,199/1973, 34,556/1973, 17,851/1977 and 4,525/1978.
However, in instances where these known backing materials are employed on a carpet base material, their performance with respect to prevention of fiber shedding is so poor that original pile yarns of the carpet are likely to be frayed. These known backing materials have the additional disadvantages that they cannot be produced to a sufficient thickness and that their dyes are likely to ooze out onto the carpet surface. They also provide insufficient dimensional stability and fixability when used for carpet tiles. They further lack in reinforcement, shape retaining performance and soundproofing performance when used for automobile carpets.
Compositions are also known in which an olefin-polar monomer copolymer, for example, ethylene-vinyl acetate copolymer (EVA), is blended with an inorganic filler. As the amount of the inorganic filler increases, the preparation of homogeneously blended compositions becomes difficult. Even if a homogeneously blended composition can be obtained, it is brittle through an increase in hardness and is also inferior in tensile properties and low-temperature performance. Such a homogeneously blended composition also has various drawbacks in that its softening temperature and flowing temperature are much raised, thereby degrading processability and consequently rendering the conditions for processing it into carpet backing severe. Such a composition is accordingly inappropriate as a carpet-backing material.
In order to improve these drawbacks, attempts have been made to use a modifier a low-molecular compound such as paraffin wax, microcrystalline wax, rosin, rosin derivatives, petroleum resin, asphalt, polyethylene wax, amorphous polyethylene, mineral oil, animal or vegetable oil, polybutene, paraffin oil, or the like. As a result, processability during blending, physical properties and processability into backing material have all been improved to some extent, thereby producing modifying effects to allow use in certain applications. Such a modifier, however, is not satisfactorily compatible so that most of it becomes separated. As the addition of such an above-mentioned modifier may cause aging and cannot sufficiently improve tensile strength, low-temperature performance or flexiblity, such a composition is incapable of being practically applied to a carpet as a backing material therefor.